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Dambach P, Bärnighausen T, Yadouleton A, Dambach M, Traoré I, Korir P, Ouedraogo S, Nikiema M, Sauerborn R, Becker N, Louis VR. Is biological larviciding against malaria a starting point for integrated multi-disease control? Observations from a cluster randomized trial in rural Burkina Faso. PLoS One 2021; 16:e0253597. [PMID: 34143831 PMCID: PMC8213177 DOI: 10.1371/journal.pone.0253597] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 06/08/2021] [Indexed: 11/29/2022] Open
Abstract
Objectives To evaluate the impact of anti-malaria biological larviciding with Bacillus thuringiensis israelensis on non-primary target mosquito species in a rural African setting. Methods A total of 127 villages were distributed in three study arms, each with different larviciding options in public spaces: i) no treatment, ii) full or iii) guided intervention. Geographically close villages were grouped in clusters to avoid contamination between treated and untreated villages. Adult mosquitoes were captured in light traps inside and outside houses during the rainy seasons of a baseline and an intervention year. After enumeration, a negative binomial regression was used to determine the reductions achieved in the different mosquito species through larviciding. Results Malaria larviciding interventions showed only limited or no impact against Culex mosquitoes; by contrast, reductions of up to 34% were achieved against Aedes when all detected breeding sites were treated. Culex mosquitoes were captured in high abundance in semi-urban settings while more Aedes were found in rural villages. Conclusions Future malaria larviciding programs should consider expanding onto the breeding habitats of other disease vectors, such as Aedes and Culex and evaluate their potential impact. Since the major cost components of such interventions are labor and transport, other disease vectors could be targeted at little additional cost.
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Affiliation(s)
- Peter Dambach
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
- * E-mail:
| | - Till Bärnighausen
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
| | - Anges Yadouleton
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Benin
| | - Martin Dambach
- Institute of Zoology, University of Cologne, Cologne, Germany
| | - Issouf Traoré
- Centre de Recherche en Santé de Nouna, Nouna, Burkina Faso
| | - Patricia Korir
- Institute of Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | | | | | - Rainer Sauerborn
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
| | - Norbert Becker
- German Mosquito Control Association (KABS), Speyer, Germany
| | - Valérie R. Louis
- Institute for Global Health, University Hospital Heidelberg, Heidelberg, Germany
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Roux O, Robert V. Larval predation in malaria vectors and its potential implication in malaria transmission: an overlooked ecosystem service? Parasit Vectors 2019; 12:217. [PMID: 31068213 PMCID: PMC6505304 DOI: 10.1186/s13071-019-3479-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/03/2019] [Indexed: 01/13/2023] Open
Abstract
The role of aquatic predators in controlling the anopheline aquatic stage has been known for decades. Recently, studies have highlighted that exposition to predation stress during aquatic development can have a profound impact on life-history traits (e.g. growth rate, fecundity and longevity) and consequently on the ability of adults to transmit human malaria parasites. In this study, we present a review aiming to contextualize the role of Anopheles larvae predators as an ecosystem factor interacting with the malaria pathogen through its vector, i.e. the female adult Anopheles. We first envisage the predator diversity that anopheline vectors are susceptible to encounter in their aquatic habitats. We then focus on mosquito-predator interactions with a special mention to anti-predator behaviors and prey adaptations developed to deal with the predation threat. Next, we address the direct and indirect effects of larval predation stress on mosquito populations and on individual life-history traits, which strongly suggest some carry-over effect of the impact of larval predation on vectorial capacity. The last part addresses the impact of human activities on larval predation. Concluding remarks highlight gaps in the knowledge of anopheline bio-ecology which may constitute avenues for researchers in the future.
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Affiliation(s)
- Olivier Roux
- MIVEGEC Unit, IRD-CNRS, Université de Montpellier, Montpellier, France. .,Institut de Recherche des Sciences de la Santé (IRSS), 01 BP 545, Bobo-Dioulasso 01, Burkina Faso.
| | - Vincent Robert
- MIVEGEC Unit, IRD-CNRS, Université de Montpellier, Montpellier, France
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Collins CM, Bonds JAS, Quinlan MM, Mumford JD. Effects of the removal or reduction in density of the malaria mosquito, Anopheles gambiae s.l., on interacting predators and competitors in local ecosystems. MEDICAL AND VETERINARY ENTOMOLOGY 2019; 33:1-15. [PMID: 30044507 PMCID: PMC6378608 DOI: 10.1111/mve.12327] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/23/2018] [Accepted: 06/15/2018] [Indexed: 05/23/2023]
Abstract
New genetic control methods for mosquitoes may reduce vector species without direct effects on other species or the physical environment common with insecticides or drainage. Effects on predators and competitors could, however, be a concern as Anopheles gambiae s.l. is preyed upon in all life stages. We overview the literature and assess the strength of the ecological interactions identified. Most predators identified consume many other insect species and there is no evidence that any species preys exclusively on any anopheline mosquito. There is one predatory species with a specialisation on blood-fed mosquitoes including An. gambiae s.l.. Evarcha culicivora is a jumping spider, known as the vampire spider, found around Lake Victoria. There is no evidence that these salticids require Anopheles mosquitoes and will readily consume blood-fed Culex. Interspecific competition studies focus on other mosquitoes of larval habitats. Many of these take place in artificial cosms and give contrasting results to semi-field studies. This may limit their extrapolation regarding the potential impact of reduced An. gambiae numbers. Previous mosquito control interventions are informative and identify competitive release and niche opportunism; so while the identity and relative abundance of the species present may change, the biomass available to predators may not.
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Affiliation(s)
- C. M. Collins
- Centre for Environmental PolicyImperial College LondonLondonU.K.
| | - J. A. S. Bonds
- Bonds Consulting Group LLCPanama City Beach, FloridaU.S.A.
| | - M. M. Quinlan
- Centre for Environmental PolicyImperial College LondonLondonU.K.
| | - J. D. Mumford
- Centre for Environmental PolicyImperial College LondonLondonU.K.
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Gotifrid GM, Urasa FM, Katunzi G, Yarro JG, Munga S, Kweka EJ. Reduced hatchability of Anopheles gambiae s.s eggs in presence of third instar larvae. BMC Res Notes 2014; 7:231. [PMID: 24725618 PMCID: PMC3991882 DOI: 10.1186/1756-0500-7-231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/04/2014] [Indexed: 11/10/2022] Open
Abstract
Background We investigated the hatchability rates of freshly laid Anopheles gambiae s.s. eggs in presence of third instars larvae. These experiments were conducted using 30 eggs in larval densities of 20, 60 and 100 larvae in microcosms. These experiments were designed to evaluate the eggs hatchability in habitats with late larvae instars of the same species (experimental) or no larvae at all (control). Freshly laid eggs of An.gambiae s.s. were washed in microcosms containing larvae of third instars in different three densities (20, 60 and 100) and likewise in control microcosms (without larvae). Eggs hatchability was monitored twice daily until no more first instar larvae emerged. The numbers of first instars larvae were recorded daily and lost eggs were considered preyed upon by third instars. Findings The findings of this study showed that egg hatchability was significantly influenced by larval density. Conclusion The findings of this study suggest that presence of larvae in habitats may significantly reduce hatchability of eggs.
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Affiliation(s)
| | | | | | | | | | - Eliningaya J Kweka
- Division of Livestock and Human Diseases Vector Control, Mosquito Section, Tropical Pesticides Research Institute, P,O,Box 3024, Arusha, Tanzania.
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Gimonneau G, Brossette L, Mamaï W, Dabiré RK, Simard F. Larval competition between An. coluzzii and An. gambiae in insectary and semi-field conditions in Burkina Faso. Acta Trop 2014; 130:155-61. [PMID: 24269743 DOI: 10.1016/j.actatropica.2013.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2013] [Revised: 11/01/2013] [Accepted: 11/09/2013] [Indexed: 12/20/2022]
Abstract
Competition in mosquito larvae is common and different ecological context could change competitive advantage between species. Here, larval competition between the widely sympatric African malaria mosquitoes, Anopheles coluzzii and Anopheles gambiae were investigated in controlled insectary conditions using individuals from laboratory colonies and under ambient conditions using wild mosquitoes in a semi-field enclosure in western Burkina Faso. Larvae of both species were reared in trays at the same larval density and under the same feeding regimen in either single-species or mixed-species populations at varying species ratios reflecting 0%, 25%, 50% and 75% of competitor species. In the insectaries, where environmental variations are controlled, larvae of the An. coluzzii colony developed faster and with lower mortality than larvae of the An. gambiae colony (8.8±0.1 days and 21±3% mortality vs. 9.5±0.1 days and 32±3% mortality, respectively). Although there was no significant effect of competition on these phenotypic traits in any species, there was a significant trend for higher fitness of the An. coluzzii colony when competing with An. gambiae under laboratory conditions (i.e. lower development time and increased wing length at emergence, Cuzik's tests, P<0.05). In semi-field experiments, competition affected the life history traits of both species in a different way. Larvae of An. gambiae tended to reduce development time when in competition with An. coluzzii (Cuzick's test, P=0.002) with no impact either on mortality or size at emergence. On the other hand, An. coluzzii showed a significant trend for reduced larval mortality with increasing competition pressure (Cuzick's test, P=0.037) and production of smaller females when grown together with An. gambiae (Cuzick's test, P=0.002). Our results hence revealed that competitive interactions between larvae of the two species are context dependent. They further call for caution when exploring ecological processes using inbred laboratory colonies in this system of utmost medical importance.
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Affiliation(s)
- Geoffrey Gimonneau
- Institut de Recherche pour le Développement (IRD), UMR 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Genetique, Evolution et Contrôle), team BEES (Biology, Ecology and Evolution of vector Systems), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France; Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545 Bobo Dioulasso, Burkina Faso.
| | - Lou Brossette
- Institut de Recherche pour le Développement (IRD), UMR 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Genetique, Evolution et Contrôle), team BEES (Biology, Ecology and Evolution of vector Systems), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France.
| | - Wadaka Mamaï
- Institut de Recherche pour le Développement (IRD), UMR 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Genetique, Evolution et Contrôle), team BEES (Biology, Ecology and Evolution of vector Systems), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France; Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545 Bobo Dioulasso, Burkina Faso.
| | - Roch K Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545 Bobo Dioulasso, Burkina Faso.
| | - Frédéric Simard
- Institut de Recherche pour le Développement (IRD), UMR 224-CNRS 5290-Université de Montpellier 1-Université de Montpellier 2 MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Genetique, Evolution et Contrôle), team BEES (Biology, Ecology and Evolution of vector Systems), 911 Avenue Agropolis, BP 64501, 34394 Montpellier, France; Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l'Ouest (DRO), 399 Avenue de la Liberté, 01 BP 545 Bobo Dioulasso, Burkina Faso.
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Reduced competitiveness of Wolbachia infected Aedes aegypti larvae in intra- and inter-specific immature interactions. J Invertebr Pathol 2013; 114:173-7. [PMID: 23933013 DOI: 10.1016/j.jip.2013.08.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Revised: 07/10/2013] [Accepted: 08/01/2013] [Indexed: 01/22/2023]
Abstract
Wolbachia are maternally inherited intracellular bacteria that frequently infect a diverse range of arthropod species. Empirical and theoretical studies examining Wolbachia invasiveness have emphasized Wolbachia effects on adult hosts, but recent studies show that Wolbachia impacts on immature hosts can be important also. Here, we have examined for effects of Wolbachia infection in Aedes aegypti. Specifically, differential survivorship is observed when young larvae (1st instar) are exposed to older Aedes albopictus larvae (4th instar) or con-specific larvae. In an additional experiment, we have examined for differential behavior and observed that Wolbachia-infected larvae differ from uninfected larvae in their reaction to light stimulation. Our results support a hypothesized effect of Wolbachia on A. aegypti larval behavior. The results are discussed in relation to the ability of Wolbachia to invade natural populations and recently applied public health strategies that target the replacement or suppression of this important disease vector.
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Kweka EJ, Zhou G, Beilhe LB, Dixit A, Afrane Y, Gilbreath TM, Munga S, Nyindo M, Githeko AK, Yan G. Effects of co-habitation between Anopheles gambiae s.s. and Culex quinquefasciatus aquatic stages on life history traits. Parasit Vectors 2012; 5:33. [PMID: 22321562 PMCID: PMC3293084 DOI: 10.1186/1756-3305-5-33] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 02/09/2012] [Indexed: 11/26/2022] Open
Abstract
Background The effective measures for the control of malaria and filariasis vectors can be achieved by targeting immature stages of anopheline and culicine mosquitoes in productive habitat. To design this strategy, the mechanisms (like biotic interactions with conspecifc and heterospecific larvae) regulating mosquito aquatic stages survivorship, development time and the size of emerging adults should be understood. This study explored the effect of co-habitation between An. gambiae s.s. and Cx. quinquefasciatus on different life history traits of both species under different densities and constant food supply in the habitats of the same size under semi-natural conditions. Methods Experiments were set up with three combinations; Cx. quinquefasciatus alone (single species treatment), An. gambiae s.s. alone (single species treatment); and An. gambiae s.s. with Cx. quiquefasciatus (co-habitation treatment) in different densities in semi field situation. Results The effect of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus was found to principally affect three parameters. The wing-lengths (a proxy measure of body size) of An. gambiae s.s. in co-habitation treatments were significantly shorter in both females and males than in An. gambiae s.s single species treatments. In Cx. quinquefasciatus, no significant differences in wing-length were observed between the single species and co-habitation treatments. Daily survival rates were not significantly different between co-habitation and single species treatments for both An. gambiae s.s. and Cx. quinquefasciatus. Developmental time was found to be significantly different with single species treatments developing better than co-habitation treatments. Sex ratio was found to be significantly different from the proportion of 0.5 among single and co-habitation treatments species at different densities. Single species treatments had more males than females emerging while in co-habitation treatments more females emerged than males. In this study, there was no significant competitive survival advantage in co-habitation. Conclusion These results suggest that co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in semi-natural conditions affect mostly An. gambiae s.s. body size. Hence, more has to be understood on the effects of co-habitation of An. gambiae s.s. and Cx. quinquefasciatus in a natural ecology and its possible consequences in malaria and filariasis epidemiology.
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Affiliation(s)
- Eliningaya J Kweka
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu 40100, Kenya.
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Ng'habi KRN, Mwasheshi D, Knols BGJ, Ferguson HM. Establishment of a self-propagating population of the African malaria vector Anopheles arabiensis under semi-field conditions. Malar J 2010; 9:356. [PMID: 21143870 PMCID: PMC3017536 DOI: 10.1186/1475-2875-9-356] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 12/08/2010] [Indexed: 11/21/2022] Open
Abstract
Background The successful control of insect disease vectors relies on a thorough understanding of their ecology and behaviour. However, knowledge of the ecology of many human disease vectors lags behind that of agricultural pests. This is partially due to the paucity of experimental tools for investigating their ecology under natural conditions without risk of exposure to disease. Assessment of vector life-history and demographic traits under natural conditions has also been hindered by the inherent difficulty of sampling these seasonally and temporally varying populations with the limited range of currently available tools. Consequently much of our knowledge of vector biology comes from studies of laboratory colonies, which may not accurately represent the genetic and behavioural diversity of natural populations. Contained semi-field systems (SFS) have been proposed as more appropriate tools for the study of vector ecology. SFS are relatively large, netting-enclosed, mesocosms in which vectors can fly freely, feed on natural plant and vertebrate host sources, and access realistic resting and oviposition sites. Methods A self-replicating population of the malaria vector Anopheles arabiensis was established within a large field cage (21 × 9.1 × 7.1 m) at the Ifakara Health Institute, Tanzania that mimics the natural habitat features of the rural village environments where these vectors naturally occur. Offspring from wild females were used to establish this population whose life-history, behaviour and demography under semi-field conditions was monitored over 24 generations. Results This study reports the first successful establishment and maintenance of an African malaria vector population under SFS conditions for multiple generations (> 24). The host-seeking behaviour, time from blood feeding to oviposition, larval development, adult resting and swarming behaviour exhibited by An. arabiensis under SFS conditions were similar to those seen in nature. Conclusions This study presents proof-of-principle that populations of important African malaria vectors can be established within environmentally realistic, contained semi-field settings. Such SFS will be valuable tools for the experimental study of vector ecology and assessment of their short-term ecological and longer-term evolutionary responses to existing and new vector control interventions.
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Affiliation(s)
- Kija R N Ng'habi
- Biomedical and Environmental Thematic Group, Ifakara Health Institute, Box 53, Ifakara, Tanzania.
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Muturi EJ, Costanzo K, Kesavaraju B, Lampman R, Alto BW. Interaction of a pesticide and larval competition on life history traits of Culex pipiens. Acta Trop 2010; 116:141-6. [PMID: 20637716 DOI: 10.1016/j.actatropica.2010.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2010] [Revised: 06/14/2010] [Accepted: 07/08/2010] [Indexed: 10/19/2022]
Abstract
Mosquito larval development occurs in aquatic habitats that are directly or indirectly exposed to chemical contaminants. Little is known about how interaction of these chemicals with other biotic and abiotic stressors impact mosquito populations. We used two levels of nutrient (low and high) and four larval densities (10, 20, 30, 40) to examine the effects of low concentrations of insecticide malathion, on Culex pipiens L. mosquitoes experiencing stress from larval competition. Addition of malathion at the high nutrient condition enhanced survival with increasing larval densities, but this effect was not observed at low nutrient condition. Males exposed to malathion were significantly larger than those from control treatments while the effect of malathion on size of females varied with larval density and the level of nutrients. Larval exposure to malathion and low nutrient resulted in significantly larger females with increases in larval densities compared with other treatments. The effect of malathion on male longevity varied with larval density and amount of nutrients. At higher densities, male longevity was consistently higher in low nutrient than in high nutrient conditions and addition of malathion in high nutrient treatment increased male longevity at the highest density. These effects are most likely attributable to release from competition among survivors after mortality from malathion and density-dependent effects. We conclude that biotic conditions of the larval habitat can alter the impact of low concentrations of chemical contaminants on mosquito populations in ways that may influence the pattern of disease transmission and the outcome of vector control efforts.
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